Which method is a more efficient use of energy to heat a building?

The use of natural gas brought into the building and burned to heat water piped through radiators is considered to be a more efficient method for heating a building for several reasons. First, burning natural gas directly produces heat that can be effectively transferred to the water and then to the air in the building through a radiator system. This method utilizes a fuel source that is generally more energy-dense than electricity, especially when electricity is generated at a fossil fuel power plant, where substantial energy is lost in transmission and conversion processes.

Additionally, heating systems that rely on direct combustion of fossil fuels can achieve higher efficiencies compared to electric heating systems. This is primarily due to the lower losses associated with direct burning rather than converting energy multiple times (as occurs when electricity is generated and then used to heat air via electric resistance).

Heat pumps, another option mentioned, can be efficient as well, but they typically rely on the external environment and require electricity to operate. While they can provide greater energy efficiency than resistive heating, their efficiency may be compromised in colder climates.

Overall, the direct combustion of natural gas allows for better utilization of energy, making it a more efficient option for heating buildings compared to relying on electricity generated from fossil fuels.